FLIES OF THE GENUS OGCODES — SCHLINGER 231 



alcohol and the dissection is completed. After about 10 minutes the 

 genitalia are placed in Cellosolve for not longer than 30 seconds, after 

 which the parts are mounted in balsam. Cover slips need not be 

 added until after the study of the parts is completed (perhaps an 

 hour, week, month, or even years), since whenever a reexamination 

 of the genitalia is desired all that is required is a drop of Cellosolve 

 applied to the top of the balsam, and in a short time a minuten may 

 be inserted and the parts rotated to the desired position for studying 

 or illustrating. 



The first-instar larvae were prepared in about the same manner as 

 the genitalia, but for quicker, clearer, less distorted mounts, Berlese 

 fluid was used in place of balsam. Larvae can either be killed first 

 in alcohol or mounted alive in the Berlese fluid. In either method 

 good mounts can be achieved only when the cover slips are applied 

 immediately and pressed firmly to flatten out the larvae. A small 

 amount of heat applied underneath the slide quickly hardens the 

 Berlese fluid and flattens out the larva to a more desirable mount. 



The maps were made by first plotting the distribution of the 

 species with black dots made with a drop-pen. After delimiting the 

 area believed to be occupied, or believed able to support the species, 

 the Zipatone overlay was applied. The paraffin base of the 

 Zipatone allows for fast, sure attachment to the map surface. 

 The Zipatone is then cut along the desired margin with a scribe. 

 The distribution maps of Nearctic species were prepared with the 

 help of certain records cited by Sabrosky (1944, 1948). All illustra- 

 tions of morphological structures were made with the aid of micro- 

 scopes and a camera lucida. All figures are greatly enlarged, 

 particularly those of the male genitalia. 



In order to rear adult parasites from their hosts, live spiders were 

 collected from suitable localities thought to have parasites present. 

 The spiders were brought into the laboratory, placed in individual 

 vials, and fed with any available insect food. In time, either the 

 host matured or a parasite larva emerged. Mature spiders rarely 

 3deld any parasites; therefore, when collecting spiders in an attempt 

 to rear parasites, one should be careful to select the immature 

 forms. 



First-instar larvae were obtained by collecting live adult female 

 flies and placing them in large jars. Although eggs are not easily 

 deposited by species of many genera of acrocerids, Ogcodes species 

 usually do so with apparent ease. The eggs are then placed in a 

 petri dish containing a piece of wet blotting paper, and in several 

 weeks the young larvae usually appear. 



